[SPARK-3454] separate json endpoints for data in the UI

Exposes data available in the UI as json over http.  Key points:

* new endpoints, handled independently of existing XyzPage classes.  Root entrypoint is `JsonRootResource`
* Uses jersey + jackson for routing & converting POJOs into json
* tests against known results in `HistoryServerSuite`
* also fixes some minor issues w/ the UI -- synchronizing on access to `StorageListener` & `StorageStatusListener`, and fixing some inconsistencies w/ the way we handle retained jobs & stages.

Author: Imran Rashid <irashid@cloudera.com>

Closes #5940 from squito/SPARK-3454_better_test_files and squashes the following commits:

1a72ed6 [Imran Rashid] rats
85fdb3e [Imran Rashid] Merge branch 'no_php' into SPARK-3454
1fc65b0 [Imran Rashid] Revert "Revert "[SPARK-3454] separate json endpoints for data in the UI""
1276900 [Imran Rashid] get rid of giant event file, replace w/ smaller one; check both shuffle read & shuffle write
4e12013 [Imran Rashid] just use test case name for expectation file name
863ef64 [Imran Rashid] rename json files to avoid strange file names and not look like php

1 files changed, 15 insertions, 0 deletions

diff --git a/core/src/test/resources/HistoryServerExpectations/one_job_json_expectation.json b/core/src/test/resources/HistoryServerExpectations/one_job_json_expectation.json
new file mode 100644
index 0000000000..4a29072bdb
--- /dev/null
+++ b/core/src/test/resources/HistoryServerExpectations/one_job_json_expectation.json
@@ -0,0 +1,15 @@
+{
+  "jobId" : 0,
+  "name" : "count at <console>:15",
+  "stageIds" : [ 0 ],
+  "status" : "SUCCEEDED",
+  "numTasks" : 8,
+  "numActiveTasks" : 0,
+  "numCompletedTasks" : 8,
+  "numSkippedTasks" : 8,
+  "numFailedTasks" : 0,
+  "numActiveStages" : 0,
+  "numCompletedStages" : 1,
+  "numSkippedStages" : 0,
+  "numFailedStages" : 0
+}
\ No newline at end of file